1. Field of Disclosure
This disclosure relates to a fuser system for a xerographic device that includes a fusing member and a pressure member. More particularly, the disclosure relates to improved self-stripping of a substrate from the fusing member as the substrate leaves a nip formed between the fusing member and pressure member.
2. Description of Related Art
In the art of xerography or other similar image reproducing arts, a latent electrostatic image is formed on a charge-retentive surface, i.e., a photoconductor or photoreceptor. To form an image on the charge-retentive surface, the surface is first provided with a uniform charge, after which it is exposed to a light or other appropriate image of an original document to be reproduced. The latent electrostatic image thus formed is subsequently rendered visible by applying any one of numerous toners specifically designed for this purpose.
It should be understood that, for the purposes of the present disclosure, the latent electrostatic image may be formed by means other than by the exposure of an electrostatically charged photosensitive member to a light image of an original document. For example, the latent electrostatic image may be generated from information electronically stored or generated, and this information in digital form may be converted to alphanumeric images by image generation electronics and optics. The particular method by which the image is formed is not critical to the present disclosure, and any such suitable method may be used.
In a typical xerographic device, the toner image formed is transferred to an image receiving substrate such as paper. After transfer to the image receiving substrate, the image is made to adhere to the substrate using a fuser apparatus. To date, the use of simultaneous heat and contact pressure for fusing toner images has been the most widely accepted commercially, the most common being systems that utilize a pair of pressure-engaged rolls.
The use of pressure-engaged rolls for fixing toner images is well known in the art. See, for example, U.S. Pat. Nos. 6,618,890, 6,289,587, 5,998,761, 4,042,804 and 3,934,113.
At the time of initial set-up of a xerographic device, the fuser system is set to be within certain specifications for, e.g., nip width, paper velocity and creep. Nip width is one of the more significant drivers of image fix and quality. Paper velocity is an important factor in paper handling. Creep, which is the release surface's extension in the nip, is important with respect to enabling the release of the paper and image from the fusing member. These specifications are set by, for example, setting a roll rotation speed for the paper velocity and setting the nip width for the dwell time and creep.
The creep is a function of the load between the fusing member and pressure member and other parameters, including the elasticity or softness of the two members. It is known that higher magnitudes of creep are effective in improving the self-stripping capabilities of the fuser system over a wide latitude of substrate media. Unfortunately, higher magnitudes of creep also mean higher levels of strain energy in the fuser roll materials when in the nip vicinity, thereby shortening the longevity of the fuser roll.
What is required is an improved method of improving the self-stripping capabilities of a fuser system for a wider latitude of substrate media without significantly increasing the strain energy within the fusing member materials.